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Tuesday, June 21, 2011

Mercury's quirks revealed by NASA spacecraft Mercury's crust contains far more sulphur than the crust of the Earth or the moon, and its magnetic field is lopsided toward the north, a NASA spacecraft has discovered. "What we are finding is that in many cases, a lot of the original ideas about Mercury are just plain wrong," said Larry Nittler, one of four scientists affiliated with the Messenger who spoke at a NASA news conference Thursday. The researchers presented some of the new images and scientific results gathered by Messenger since it became the first spacecraft to enter orbit around the closest planet to the sun on March 17. Mercury is the only rocky planet in our solar system besides Earth that has a magnetic field, and one of Messenger's surprising findings so far is that Mercury's magnetic field is not a miniature version of Earth's, said Sean Solomon, principal investigator for the mission at the Carnegie Institution of Washington. "The magnetic field in the northern hemisphere is stronger and different from that in the southern hemisphere," he added. Mercury's magnetic equator is north of the planet's geographic equator by roughly a fifth of the planet's radius. That means its south pole is far more exposed to charged particles than its north pole, and may help explain the presence of the planet's exosphere – a tail of elements such as sodium that are kicked off the surface by charged particles from space. Messenger has also found that Mercury's crust contains less aluminum and more silicon than the Earth, and 10 times as much sulphur than either the Earth or the moon. "Mercury most likely formed from building blocks that were fundamentally chemically different from those that formed the Earth and moon originally," Nittler said. He added that Mercury's high sulphur content could help illuminate the nature of volcanic activity on Mercury, since explosive volcanoes are closely linked to sulphur-containing gases on Earth. One of Messenger's goals is to test a hypothesis proposed 20 years ago about why there appears to be water ice on a planet so close to the sun. Scientists first proposed 20 years ago that bright spots on Mercury's poles, seen by radar telescopes on Earth, might be water ice trapped in craters that kept them permanently in shadow, beyond the sun's reach. Solomon reported that Messenger has now mapped the topography of much of Mercury's surface. The mapping shows that the parts of some craters in permanent shadow coincide with the location of the deposits that are thought to be water ice. "The first scientific test of that hypothesis using Messenger data from orbit has passed with flying colours," Solomon said.

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Forget the moon and Mars: Pentagon spending $1 million for ideas about how to fly to a star The research agency in the U.S. Defence Department that helped foster the Internet wants someone to dream up a way to send people to a star. The winner will get half a million dollars for the idea. This month 150 competitors answered the federal government's initial call for private sector cosmic ideas. Officials say some big names are among those interested. The plan is to make interstellar travel possible in about a century. The Defence Department is known for big spending and big ideas. It devised a space-based missile defence system in the 1980s known as "Star Wars." Its new trademarked 100-year Starship Study concept comes from the Defence Advanced Research Projects Agency. The agency is spending a total of $1 million on the project. After presentations are made at a conference in Orlando, Florida, DARPA will decide in November who gets the money. The grant would be "seed money" to help someone start thinking about the idea and then get it off the ground in the private sector, David Neyland, director of DARPA's tactical technology office, said in a Thursday teleconference. This is not about going to a nearby planet, like Mars. And it is not about using robotic probes, which does not interest the Defence Department, Neyland said. But even the nearest star beyond our sun is 25 trillion miles (40 trillion kilometres) away. The fastest rocket man has built would take more than 4,000 years to get there. This is not just about thinking about new rocket methods, Neyland said. It is also about coping with extended life in space, raising issues of medicine, agriculture, ethics and self-reliance, he said. Among those who showed an interest in the project earlier this year is millionaire scientist Craig Venter, one of those who mapped the human genome and is now working on artificial life and alternative fuels. "We want to capture the imagination of folks," Neyland said. Not everyone agrees with spending money this way. Steve Ellis, vice-president of Taxpayers for Common Sense, said, "When you look at the universe — pun intended — of things we have to spend money on, this has to be pretty down on the priority list."